java-sql-schema-migrations

Intent

Provide a repeatable, tool-agnostic playbook to evolve SQL schemas safely in production with minimal downtime and minimal blast radius. The default strategy is expand/contract with backward compatibility at every intermediate step.

Scope

In scope

• Schema evolution (tables/columns/indexes/constraints) with zero-downtime or near-zero downtime
• Rollout sequencing: application deploy(s) + migration(s) + backfill(s) + cleanup
• Guardrails: locking risk, long-running DDL, verification, rollback strategy
• Flyway/Liquibase conventions (but the approach works with any migration runner)

Out of scope